The present invention relates to a toolholder in which a cutting insert with a central hole is mechanically clamped against a pin that enters the hole of the insert. The clamping means comprises a wedge clamp which is acting on an edge surface as well as on the top surface of the insert, thus urging the insert forwardly against the pin and downwardly against a bottom supporting surface. The present clamping means will enable clamping of both single and double-sided inserts of basic negative shape having chipbreakers at both its top and bottom surfaces.
In pin-type holders the insert is located in clamped position against a pin in the insert-receiving site of the holder. The insert is brought into clamped position by a clamp device disposed between the pin and an abutment surface of the holder facing the pin. In U.S. Pat. No. 3,905,081 there is disclosed such a cutting tool in which the clamping device comprises two distantly provided extensions formed as convex ridges, one of which is brought into abutment with the top face and one of which is brought into contact with an edge face of the cutting insert.
It has been found that clamping devices of the type described above do not in all respects satisfy the demands of tools used in industry today. One essential requirement is that the size and direction of the clamping force be able to secure the insert in its location against a minimum displacement while being subjected to a maximum cutting force acting on the cutting edge. It is another requirement to secure the insert so that vibrations or intermittent cutting sequences do not reduce the clamping force or produce premature fatigue failures of components and insert locations of such toolholders. It is furthermore desirable to provide a holder such that its components do not reduce the chip flow, or the supply of cool medium supply to the cutting insert, or the degree of engagement of the insert with the workpiece to be cut. These requirements are of utmost importance in turning and copying toolholders where the active cutting edges converge under an acute angle forwardly towards a cutting tip.